Tuning device for radio receiving sets



Aug. 7, 1928.

P. w. wlLLANs ET AL TUNING DEVICE FOR RADIO RECEIVING SETS 2 sneaks-sheet 1 Filed J an. 14, 1925 Aug. 7, 1928.

P. w. wlLLANs ET AL TUNING' DEVICE FOR RADIO RECEIVING SETS Filed Jan. 14, 1925 2 Sheets-Sheet 2 INVENTOR P.W.WILLANS AND ARTHUR STANLEY ffy( IL/Mi) ATTORNEY Patented Aug. 7, 1928.

UNITED STATES PATENT OFFICE.

PETER WILLIAM WILLAN S, OF TOWCESTER, AND ARTHUR STANLEY, OF BLOOHPIELD, NEAR CHLEMSFOBD, ENGLAND, ASSIGNORS TO RADIO CORPORATION OF AMERICA,

A CORPORATION 0F DELAWARE.

TUNING DEVICE POB. RADIO RECEIVING SETS.

Application led January 14, 1925, Serial No.

This invention relates to tuning devices for radio receiving sets and its object 1s to provide simple means whereby the wave length of circuits can be readily. and progressivel varied within wide l1m1ts.

Accor ing to this invention a variometer vcomprises two pairs of flat spiral coils, .the two coils of one pair being exactly similar to one another and mounted coaxially with one another, while the two coils of the other pair are also identically similar to one another and are mounted coaXially with one another, the two axes being parallel to one another and the two coils of one pair being of diiierent inductance from those of the other, and upon an axis which is parallel to these two axes and equidistant from them is mounted a shield or screen in such a way that it can be rotated so as to lie between the two coils of either pair and thus screen a greater or less part of one coil from the other coil of the pair. Thus the effective inductance of either pair will depend upon the position of the shield. The shield is substantially in the form of a sector of a circle but by suitably shaping it, it is possible to obtain a change of wave length which varies directly with the angular movement of the shield.

In conjunction with this variometer may be employed a four position switch by means of which either pair-can be included in circuit as desired and the two coils of either pair may be connected in series or in parallel.

Our invention is illustrated by the accompanying drawings in which Fig. 1 is a perspective view of a variometer made in accordance with this invention; Fig. 2 is a diagrammatical representation of the invention showing the switch for connecting the coils in circuit; Figs. 3, 4 and 5 are diagrammatical representations similar to Fig. 2 showing the switch in its different positions; and Fig. 6 is a view showing the scale for determining the value of the inductance.

L, L1, are two coils which are similar to one another and are mounted coaxially and S, S1, are two other coils which are similar to one another and are mounted coaxially, the axes of the two pairs of coils being parallel to one another. Midway between the two axes and parallel to them is a spindle A which carries a shield B and 2,368, and in Great Britain January 16, 1924.

which can be turned by means of a knurled head C so as to cause a greater or less portion o the -shield as desired to lie between the coils L, L1, or between the coils S, S1, so that the effective inductance of either pair of coils will depend upon the position of the shield.

In conjunction with such a variometer we preferably employ a switch, by means of which the coils S, S1, may be connected in circuit either in series or in parallel or the coils L, L1, may be so connected. The switch comprises a number of conducting segments D arranged round an insulating holder. A convenient method of forming these segments is to mount upon the holder a complete ring and then to divide this ring by saw cuts into the required number of segments. Each segment is secured to the holder by a screw or screws which are screwed in before the saw cuts are made. This method of construction has the advantage that the segments must come in their correct sequence whereas if the segments were cut to size before they were fixed in position it would be necessary to have many diierent sizes and there would be risk of their being fixed in the wrong sequence.

The screws may also secure in position tabs to which external connections can be soldered.

The switch also comprises a rotatable part E of insulating material and carrying ten equally spaced brushes F1 to F10, each of which contacts with one or other of the segments D1 to D18 as the part E is rotated.

Certain of the segments are interconnected as shown by wires G1L to G4 and certain of thelprushes are interconnected by wires H1 to 4.

In the arrangement shown the arran ement of the segments may be most readily described by considering the holder as divided into 40 sections. In Fig. 2 segment D1 occupies approximately one section. The second section on the holder proceeding in a clockwise direction has no conducting segment; the third, fourth, fifth and sixth sections of the holder are occupied by segments D2, D3, D4 and D5 respectfully, the segments being separated by saw cuts to insulate them. The seventh section of the ring has no segment. The next four sec- 721) and another sing tions 8 to 11) of the ring are occupied by a singe wide se ent -D. width segments 1 and D11 separated by a saw cut occupy the next four sections v4(12 to 15). Following these is a single width blank space (section 16) on the ring, then se ent D9 (section 17 another single width blank space (section 18) the single width se ents D10 and D11 (sections 19 and 20) ollowed by another space (section le width segment, D12 (section 22 and a sin le widt-h space (section 23). he remainder of the circumference is occupied'by segments D111 having a width of four' spaces D11 and D1, two spaces each (sections 28 to 31), D10 four Spaces (sections 32 to 35) and 11 an D11 two spaces each (sections 36 to 39). D1s and D1 are separated by a space of approximately one section (sect-ion 40). Segments D1 and D3 are conductively connected by G1 which has a lead T1 extending to one end of coil L. Segments D2 and D1 are connected b 2 whic one end of coil g1. segments D1 and D12 and a. lead T1 connects from G3 to one end of coil S. T0 is a lead connected to segment D0 which extends to the terminal N. Segment D1 is connected by lead T0 to the other end of coil L opposite the connection of lead T1. Lead T1x is connected between segment D, and the other end of coil S1.

' connected together by conductor G1 and the by lead T11 "Brushes F1,- F3 and coil L1. Segment D10 is connected to G1 and thus to D12 and D1.

Segment D13 is connected tc terminal M by lead T0. The connection to D11, D11 and D10 will be described'subsequently.

Segment D11 is connected by lead T10 to the other end of coil L1 and D13 is connected to -the other end of coil S.`

F10 are connected together by conductor H1. Brushes F2 and F0 are connected together by H2. Brushes F1, F, and F1 are connected together by conductor H1. Brushes F,3 and F0 are connected together by H1.

The part E has fast with it a handle J (Figure 6) by which it can be turned into any one of four positions as shown in Fig-4 ures 2, 3, 4 and 5.2 In the position shown in Figure2 it. will be seen that the coils S, 1, are connected in parallel between the points M N, while the coils L, L1 are unconnected.

The two parallel circuits from M to N maybe traced as follows (1) Conductor T0, segment D13, brush F1,.conductor H1, brush F1, segment D10, conductors Gs and T1, coil S, conductor T11, segment D11, brush F10, conductor H1, brush F1, se ent D1, conductor T1 to terminal N; (2 conductor T0, segment D13, brush F1, conductor H1, brush Two double d has a lead T2 to F A conductor G1, connectsl Segments D, and D11 arev atter is connected by lead T, to one`end of L 3 points M N 1 nected..

F1, segment D1, conductor T1, coil S1, coiluctor T2, conductor G2, se ment D2, brush F1, conductor H1, brush conductor T1, to terminal N. connected because the segment D11 connected thereto' is not in contact with a brush and the other segments D0 and D11 connected to coil L1 is dissegment D1,

the opposite ends are likewise'out of contact with brushes; It will be noted that segments D1, D1 and D, which connect to coil L are likewise out of contact with the brushes as a result of which coils L and L1 are out-of the circuit as stated heretofore.

In position 2 shown in Figure 3 the coils 1, are connected in serles between the points M N and the coils L, L1, are again lmconne'cted. he series circuit from point M to point N throughcoils S1 and S2 may be traced as follows: 1

From terminal M to segment D11', brush F1, conductor H1, brush F1, segment D1,

(sections 24 to 27), S S

conductor T1, coil S1, conductors T2 and G2,

segment D1, brush F2, conductor H2, brush c, segment D12, conductors G, 'and T1', coil S, conductor T11, segment D11, brush F10, conductor H1, brush 1, segment D1, co ductor T5 to terminal N. Coil L1 is disconnected because no brush is in contact with segments D0, D11 or D11 which are connected to the ends of the coil L1.- Likewise coil L is disconnected because segments D1 and D1 and D3 are not in contact `with brushes. A

In position 3 shown in Fi re 4 the coils L1, are connected in para lel between the points M N and the colls S, S1, are unconnected. Egint M to N through traced as follows: (l) Conductor T1, segment D11, brush F1. conductor H1, brush F1, segment D0, conductor T8, coil L1, conductor T10, segment D11, brush F10, conductor H1, brush F3, seginent D0, conductor T5 to terminal N. (2)

coils L1 and L2 may .Conductor T0, segment D11, brush F1, conductor H1, brush F1, segment D1, connection T0, coil L, connection T1, conductor G1, segment D1, brush F1, conductor H1, brush F3, segment D1, connection T1, to N. S is disconnected because the segment D11, is not .in contact with a brush. Likewise the coil Sl which is connected to segments D1, D, is out of contact with any brush.

In position 4 shown in Figure 5 the coils L, 1, are connected in series between the and the coils S, S1, are uncon- The series connection of coils L1 and L2 may be traced as follows From M through conductor G11, to segment D13, brush F1, conductor H3, brush F1, segment D1, conductor T0, coil L, conductor T1, connection G1, segment D1, brush F2, conductor H2, brush F0, segment D11, conductor G1, connection T3, `co1l L1, con- The two parallel circuits' from D1] and nection T10, se ent D12, brush F10, connection H1, brush 3, segment De, connection T, to terminal N. Coil S is unconnected because the segment D11, is connected to one end of it through conductor T11 is not in contact with a brush; Likewise coil S1 which is connected to segments D2, D, and D,1 is not in contact with the brushes.

The value of the inductance of either pair of coils S, S1, and L, L1, may be read on a scale K which is fast with the head C against a fixed index U for the coils L, L1, and V for the coils S, S1.

In order to avoid possibility of mistake by using the wrong index the part E is provided with two lugs e one of which masks one of the indices U in any position of the switch.

The connection of the coils L, L1, S, S1, is effected by means of eight only of the ten brushes, those marked `Fs and F9 not being required for this purpose. They may, however, be employed to connect reaction coils Rs, RL, and if they are required for this purpose three conducting segments Q1, Q2, Q3, are mounted on the fixed art.

The circuit of the reaction coil Rs in Fig. 2 is from terminal O, lead T12, segment D16, brush F9, connection H2, brush F8, lead T13, segment Q2, lead T11, coil RS, leads T15 and T16, segment Q1, lead T1.l to terminal P. Coil RL is disconnected as the segment D14 connected to the lower end is not in contact with a brush. In Fig. 3 the circuit connection is likewise through Rs through the same connections.

In Figs. 4 and 5 the coil RL is connected in circuit between O and P the connections being lead T12, segment D16, brush F2, con-. nection H1, brush F2, segment D11, lead T18, segment Q1, lead T19, coil RL, ,lead T15, segment Q3, lead T1., to terminal P. Rs is disconnected because segment D15is not in contact with a brush.

Having described our invention what we claim is as follows l. A variometer comprising two pairs of inductance coils, the two coils of each pair being similar to one another and mounted coaxially, and an irregular shaped shield mounted upon an axis parallel to the axes fi' the coils in such a way that it can be rotated so as to `lie between the coils of either pair, whereby the inductance of the variometer may be varied in accordance with a predetermined law.

2. In a tuning device for radio receiving sets, the combination of a variometer as claimed in claim 1 with a four position by which the coils of either pair can be connected in circuit either in series or in parallel, substantially as described.

3. In a tuning device for radio receiving sets, the combination of a plurality of pairs of coils, a single means for selectively connecting said coils in series or in parallel, and means to vary the inductance between the coils of said pairs, the coils of said pairs being permanently xed relative to each other y 4. In a variometer, the combination of a plurality of pairs of coils iXedly mounted 0n mutually parallel axes, means for connecting the desired pair of said plurality for active use, a manually operable member having angular movement, and means associated with said member to vary the inductance of the coils in active use.

5. In a variometer the combination of a plurality of pairs oi coils, means for connecting the desired pair of said plurality for active use, a shield mounted for angular displacement and adapted to be interposed between the coils of each of said pairs for varying the inductance of the active coils, and manual means for moving said shield, said shield being shaped so that unequal areas thereof may be interposed between the coils by equal increments of movement of the manual means.

6. A variometer comprising a plurality of ,pairs of inductance coils, the two coils of each pair being similar to one another and mounted coaxially, and a shield mounted in such a way that it can be adjusted to vary the inductance of any of said pairs of coils.

7. A variometer for tuning a circuit comprising a plurality of pairs of inductance coils, the two coils of each pairv being similar and the coils of different pairs being dissimilar, means for connecting the coils of any pair in the circuit to make that pair active and means for varying the inductance of the coils of the active pair.

8. A variometer, according to claim 4, in which the means for connecting the desired pairs of said plurality for active use also is adapted to vary the inductance of the coils in active use.

9. A variometer for tuning a circuit comprising a plurality of pairs of inductance coils, the coils of each pair being similar and the coils of diierent pairs being dissimilar, means or connecting the desired coils of said plurality of pairs for active use in said circuit and for varying the inductance of the coils in active use, and a second means for further varying the inductance of the coils in active use.

10. A variometer for tuning a circuit comprising a plurality of pairs of inductance coils, ixedly mounted on mutually parallel axes, the coils of each pair being similar and the coils of different pairs being dissimilar, means for connecting the desired coils of said plurality of pairs for active use in said circuit and for varying the inductance of the coils in active use, and a second means for further varying the inductance of the coils in active use without changing the relative positions of the coils.

11. A variometer for tuning a circuit comprising a plurality of pairs of inductance coils, the coils of each pair being similar and the coils of different pairs being dissimilar, means for connecting any pair of the coils in parallel for one adjustment and in series for another adjustment, said means also disconnecting the remainder of said coils for both adjustments, and a second means for kvarying the inductance of the connected coils for either adjustment.

variometer, according to claim 11, 15 in which the, second means consists of a metallic shield adapted to be manually moved to vary the inductance. v

13. A variometer, according to claim 11, metallic shield interposed between the coils of the connected pair. i PETER WILLIAM WILLANS. ARTHUR STANLEY. l f

which the second means consists of a 20 l 

